Luffing crane



April 6, .1943, v J. w. DEIST 2,315,942

LUFFiNG CRANE Filed Sept. 29, 1942 5 Sheets-Sheet l M'AQ' YZZIZZ X77;w/Mwd April 6, 1943. w DElSTT 2,315,942

' LUFFING CRANE I Filed Sept; 29, 1942 5 Sheets-Sheet 2 INVEN'I'OR April6, 1943.

J. w. DElST LUFFING CRANE Filed Sept. 29, 1942 5 Sheets-Sheet 5 III II3" a INVENTOR QW'WMQMX April 6, 1943. J. w. DEIST 2,315,942

LUFFING CRANE Filed Sept. 29, 1942 Shee'ts-Sheet 4 I INVENTO April 6,1943. w IDE|ST 2,315,942

' LUFFING CRANE Filed Sept. 29, 1942 5 Sheets-Sheet 5 6M1 day/MatPatented Apr. 6, 1943 Joy Wendell Deist, Mount Lebanon, Pa., assignorPittsburgh, Pa., a corto Dravo Corporation, poration of PennsylvaniaApplication September 29, 1942, Serial No. 460,051

1 Claim.

This invention relates to lufiing cranes and,

generally, to structures that include pivotally require to be swung Pwermounted parts that fully. Such structures may, for example, bedraw-bridges or the gates of locks. The invention, however, has beendeveloped in the building of lufiing cranes, and in such specificassociation it will here be shown and described. The

objects in view are speed and accuracy in operation and durability.

In Letters Patent of the United States, No. 2,188,686, granted January30, 1940, onthe application of Bernard H. Kersting and Hans Enard, meansare described in association with a lufling crane for efiecting thelumng movement. The present invention consists in improvement on thelufiing means of the said patent.

In the accompanying drawings Fig. I is a view in side elevation of agantry crane of turret type, mounted to travel upon rails, in which theluillng means of this invention are. employed; Fig. II is a fragmentaryview to larger scale, showing in plan the lufiing-mechanism; Fig. III is.a fragmentary view in side elevation of the luiiing mechanism, the wallof the mechanism being broken away in part, and the structure beyond thewall shown in vertical section in the plane of the axis of one of thescrews; Fig. IV is a fragmentary and sectional view to yet larger scale,on the plane IVIV, Fig. IH; Fig. V is, a view in section, on the planeindicated at V- V, Fig. IV (from the showing of Fig. V, however, certaindetails of structure are lacking); Fig. V1 is a sectional view to yetlarger scale, on the plane indicated at VI-VI, Fig. II; Fig. VII is aview to yet larger scale, presenting in end elee vatlon the lumngmechanism that in Fig. II is shown in plan; Fig. VIII is a diagrammaticview in side elevation of a draw-bridge which includes a pivotallymounted element, and to which application is made of the swinging meansof the invention. I

Referring, first, to Fig. I, the crane is mounted upon a base, in thisinstance a platform I mounted to rotate turret-like upon a derrick 2.The crane includes a jib 3 pivoted upon a horizontal axis to the base at4 and adapted to swing vertically upon such pivotal mounting. Suchvertical swinging is termed lufling. From a drum ("not shown, butrotatably mounted on platform I", as is usual) a hoist line 8 extendsthroughout the length of the jib and supports, in a suitably formedbight, a block I. Upon this block the load is hung.

screws 9 thus form a triangle (called The jib 3 of the' crane is, as inFig. I it is shown to be, a truss structure, of general triangularoutline, pivoted at one comer of the triangle at 4 upon the base I00.This triangular truss structure includes the basal chord memher 8.. Athird member (in this case and for the purposes of invention a multiplemember, consisting of duplicate screws 9, 8) is, througi intermediateparts, pivoted at one end (on a horizontal axis of pivoting) to theotherwise free end of member 8 of the truss-formed jib (at l0) and is,through intermediate parts, pivoted at the opposite end (and on ahorizontal axis of pivoting) to the base I00 at the point ll, remotefrom the pivot point 4. The base Hill, the chord member 8, and theduplicate in the industry an A frame). Of this triangle of members, theeffective length of one ,side (formed by .the duplicate screws 9) isvariable; and,"by variation of the effective length of this member, thejib is'swung and lufiing is effected.

In the 'Kersting and Enard patent alluded to the screw 9 is a singletension member and the stresses of' service are centered in the axis ofthe screw. ,The trussed jib 3 is a three-dimensional structure, ofsubstantial extent in the direction perpendicular to the plane of theside elevation, Fig. I. Referring to Fig. 11, the truss of the jib 3will be seen to include, not the member 8 only, nor even the pair ofmembers 8, 8,-but a second pair 8*, 8 and a duplicate and more widelydistant set of members 8', 8 and 8, 8. The invention consists in anelaboration of the lufiing means of the Kersting and Enard patent and anorganization of the elaborated parts, by which the three-dimensional jibmay be more effectively luiIed.

I have prepared duplicate screws 9, one for each of the two sets oftruss members 8, 8 8, 8 and 8 8, 8, 8, and have centered the screws, onein each of the two groups, as sufilciently illustrated in Fig. II. Thetwo screws, so severally centered, are geared to an interconnectingcross-shaft, whereby simultaneity in rotation and at equal speed isinsured. And by such means the assembled structure is re-enforced,'to'resist racking strains, and security, accuracy of operation, anddurability are enhanced.- I have used the term duplicate screws 9, andthe word duplicate will not be misunderstood. With such interconnectionas that shown in Fig. II, the two screws, to be effective in the mannerdescribed (cf. Fig. VII), will be oppositely threaded. Subject to thisdetail of |6 a motor trated in Fig. VI, the shaft 9 couplings I 6!, 05

oppositely directedthreads, thescrews are duplicates.

Each of the two screws 9 is oppositely threaded at its two ends, andeach carriesxupon its oppositely threaded ends two "oppositely threadednuts, l2 and II. The nuts are pivotally mounted in pairs of links, l4,l4 and i6, I6. that move in runways 26 in two duplicate frames l6, l6,and in their mountings are secured against rotation. The links arepivoted-the links I4 at one end of the screws 6 to the paired trussmembers 6, 8, 6, 8' etc., and the links ii are pivoted to acorrespondingly elaborated anchorage in base I (note in Fig. IV theelaboration I, I I, I). It is manifest, then, that; as the screws '9, 9are rotated in one direction or the other and the pairs of links drawntogether or spread apart, the eflective length of the paired screws as amember of the A frame is diminished or increased, and the jib 3 is swungupward or downward.

As appears in Fig. VI, each of the screws 6 may conveniently -be formedoftwo severally formed andessentially duplicate halves placed end to endand bolted together and carrying bolted to them a gear wheel 9 l. Uponeach frame I6 is mounted, and from the driven shaft I80 of ing includesa pinion 92, whose shaft carries a bevel gear 93; and the duplicatebevel gears so associated, one with each of tus of the two shafts 9, arein mesh with duplicate complementary bevel gears, both borne by asingle, transversely extending shaft 94. For purposes of assembly andadjustment, separable and 96 are conveniently provided. By suchprovision the two motors [6 cooperate in rotating the two screws 9, 0 insimultaneity.

It will be understood that, even though the direct loads on theduplicate screws 9, 9 ,are substantially equal, the power required todrive one of the screws may be different from the power required todrive the other. This is due to inequalities in the frictionalresistance between the relatively moving parts of the two screw assemblies, caused particularly by unavoidable variations in the lubricationof the parts, and by minute variations in the contours of the threads ofthe screws. The cross-shaft 94 operates, manifestly, to equalize thework imposed upon the two motors, and thus it is possible to constructthe shafts and the lufllng mechanisms muc lighter and at less cost thanotherwise. r

The duplicate frames l6, s0 assembled with links l4, l4, l5, l afford afloating runway and a tension-resisting member for the links and supportfor the motors IS. The frames are formed of steel plate and are of thegeneral troughshape shown. The two frames are interconnected by awalkway I63. In the ensuing claimthe term frame will be employed toinclude such a multiple part. Screws 6 are prolonged in shaftlikeextensions 90 of reduced diameter that turn in frame-bornebearing-blocks I62. And upon these blocks the bodies of the screws makeendwise abutment. Manifestly, it is only the reaches of screws 9 betweenthe nuts l2 and I8 that are subject to the tension stresses of theloaded crane; and, of course, if the screws break, they will breaksomewhere in the interval between the nuts. In the event of such screwfailure, the

ends of the broken screw become compression the motor, through thegearing .illusis driven. The gearthe driving apparamembers and transferthrough the blocks I02 to the body of the frame II the load-sustainingtension. Thus the frames I6, normally serving as runways and motorsupports, are. adapted in emergency to become effective load-sustainingmembers, preventing undue harm to the apparatusc and guarding workmenfrom serious danger. Provision is made between nut and screw. tions uponthe-degree of in the preparation of material and the fabrication ofparts give value to this provision. The nut has gimbal mounting in thepairs of;,links; and, according y, underthe stress transmitted betweenscrew and link, the nut adjusts itself upon the screw, and stress thatotherwise might The practical limitabe concentrated at onepoint isdistributed gears of the duplicate around the circumfere be of theinterengaged threads. The gimbal mounting is found in a cylindrical cup22 with-a bottom orifice through which, in the assembly, the screw Iextends, and within which the nut is arranged. Externally, the cup isprovided with trunnions 24, by which it is pivotally mounted in theassociated pair of links (l4, l4 or l6, l6). Internally, the cup isprovided with transversely extending cylindrical biisses. convenientlyformed as pins 26, welded in orifices in the cup walls. The axes oftrunnions 24 and of pins-2| are angularly displaced at a angle, withrespect to the axis of the cup (and of shaft 6) as a centre. Upon thebosses 26 the -nut makes thrust bearing, the bearing surface of the nut'being, correspondingly cylindrical in shape. Elsewhere than over thethrust surfaces specified, the nut has clearance, from the surfaces ofthe cup.

The nut is compound, and consists of the con-- centrically arrangedparts 20 and 21'. It is the outer of these two parts that engages thecup 23 over the cylindrical-bearing surfaces specifled; it is the innerpart 20 that is the threaded part and that immediately engages thethreaded stem 6. The inner tingzengagement with the outer 'over theshoulder Upon the part 20 a supplementary nut 36 is mounted. Thesupplementary nut is cut away in part, as indicated at 22 (Fig. IV),exposing the assembled threads of nut'and screw. threads within the part26 are so proportioned as to fill the complementary threads of thescrew: the threads in the space between the opposed'surfaces of nut andscrew. When the parts the faces of the threads of the supplementary nutstand away from the faces of the threads of the screw. In consequence,it is the nut part 26 through which alone the stresses of service arenormally transmitted. As in continued use the interengaged surfaces wearaway. the spaces at which the surfaces oi the supplementary nut 26 standaway narrow. This narrowing of: space is visible through thecut-away'space I2. Thus a tell-tale is provided, by which determinationmay be made, when the nut part 20 is so far worn as to requirereplacement.

The nutpart 26 will ordinarily be formed of bronze; but thesupplementary nut I6, serving the described purpose, not of tell-talemerely;

forthe distribution oflstress perfection attainable indicated at 26.

part makes stress-transmit- The supplementary nut 30 are so proportionedas normally to leave a small are initially assembled,

frame is diminished or increased; and arm 3 is raised or lowered. Theprovision of duplicate screws 9, arranged in parallelism and spacedapart in the direction of the breadth of the truss that constitutes thejib 3, adjustable to equality in effective length, and, when adjusted,adapted to be rotated in simultaneity and at equal speed, ailords anassembly that is rugged, braced against racking stress, and of notablerigidity and durability.

In Fig. VIII a draw-bridge is diagrammatically shown, consisting of twohalves 40 severally mounted plvotally upon opposed bridge-heads ill; andadapted to be swung vertically between fullline and dotted-linepositions. In this case, also, each bridge half is in structure atrussthat includes a chord member 80, and the truss has breadth: itextends in a third dimension, perpendicular to the plane of view of Fig.VIII. Between the distal end of chord 80 (the end remote from the pointof pivoting) and a pivot to mountedon the bridge-head 50 at an intervalfrom the pivot I0 0! the chord member 80, such a structure as thatalready described may be introduced. By means of such astructure thedraw-bridge halves may be raised and lowered. By virtue of theduplication of the screws 8 o! the structure, connected to therelatively movable parts and spaced from one another across-the breadthof the structure, the ends already named of rigidity and durability aregained.

I The invention in like manner the swinging of single-spandraw-bridges.- It is manifestly applicable to the swinging of the gatesof canal locks; and generally to the swinging of pivotally mountedstructures that require to be powerfully swung.

I claim as my invention: Means for swinging a structure pivotallymounted upon a support and having extension in the direction of the axisof pivoting, such means including a frame, two pairs of carriagesmounted in the frame, the'carriages of each pair in 'alignment, and thetwo pairs arranged in succession in. the direction of the said axis ofpivoting, the carriages mounted-for longitudinal movement in the frame,one carriage of each pair being pivoted to the swinging structure andthe other carriage of each pair being pivoted to the support at pointsremote from the said axis of pivoting, two pairs of nuts mounted onepair in each of said carriages, two screws simultaneously engagingseverally the two nuts of the two pairs and adapted on rotation toeffect the drawing together and the separation of the so-engagedcarriages, two motors, d iving connections from the motors severally tothe two screws, and a crossshaft interconnecting the two screws, wherebythe two motors co-operate in rotating the two screws and the loadimposed upon the motors is equalized between them.

a JOY WENDELL DEIST.

is applicable to

